Evangelism has always been at the heart of the Christian mission
At Pentecost, the Holy Spirit descended upon the Apostles, who then went on to baptize 3,000 people were that same day, as recounted in the Book of Acts. We read that these early Christians joined together in community, “and every day the Lord added to their number those who were being saved.” Indeed, the numbers of Christians exploded not only among Jews, but also Gentiles; not only in Jerusalem or Rome, but throughout the Empire.
One factor to which this rate of conversion can be attributed is Hellenism – that is, the spread of Greek culture. Hellenists lived in a great many different cities, providing an avenue for information of the new faith to be spread. Church historian W. H. C. Frend explains, “The rapid spread of Christianity must have been due to the news passing through the network of Hellenistic synagogues radiating from Jerusalem” (The Rise of Christianity, 89). Similarly, the expanse of the Roman Empire provided the infrastructure for evangelization, facilitating travel and communication between Christian communities. At its height in the 3rd century A.D., the Roman Empire covered territory from what is now Great Britain, south to the Mediterranean and east to Mesopotamia.
However, crucial to this expansion is the fact that spreading the Gospel is central to the mission of Christianity. Christ told his disciples, “Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit” (Matthew 28:19). The Apostles and the many Christians who came after them believed that everyone should hear the truth of the Gospels. St. Paul, in particular, made His way through the known world, preaching and communicating the Word of God (read more about St. Paul's apostolic missions in Acts 13-21).
The Catholic faith has continued to grow throughout the world, reaching out as far as “the ends of the earth” in South America or China – a phrase used by the recently elected Pope Francis in reference to his own homeland. The Second Vatican Council, in Lumen Gentium, instructs us about the continued missionary role of the Church: “For the Church is compelled by the Holy Spirit to do her part that God’s plan may be fully realized, whereby He has constituted Christ as the source of salvation for the whole world. By the proclamation of the Gospel she prepares her hearers to receive and profess the faith.”